Analysis and Optimization of Dysprosium-Doped Yellow Fiber Lasers for Ophthalmology Applications

Lasers operating within the yellow range of the visible spectrum are widely adopted in many fields, ranging from astronomy to medicine, particularly for the safe treatment of macular retinopathy. The interest in Dysprosium-doped Fiber Lasers (FLs) is growing due to advances in blue pump laser diodes and high-quality fluoride fibers, to be used as the active medium, with the promise of cost-effective, compact and reliable yellow emission. In this study a matrix-based model based on rate equations is used to thoroughly investigate the impact of Excited State Absorption (ESA) on the performance of tunable yellow FLs, revealing its significant effect on efficiency and tunability. Additionally, the potential of mid-infrared cascade lasing to mitigate ESA effects was investigated. Results provide insights into the enhancing of the output power behaviour of yellow FL sources through careful selection of output mirror reflectivity and active fiber length. This work anticipates significant improvements in the achievable performance via cascade lasing, paving the way for future experimental validation.